Flexible phenolic-formaldehyde resin compositions



FLEXIBLE PHENOLIC-FORMALDEHYDE RESIN COMPOSITIONS Robert Steckler,Chagrin Falls, Ohio, assignor to General Aniline & Film Corporation, NewYork, N.Y., a corporation of Delaware No Drawing. Filed Sept. 5, 1958,Ser. No. 759,123

'10 Claims. (Cl. 26019) The present invention relates to a plasticizedphenolicformaldehyde resin composition having excellent flexibility andresistance to flaking or cracking.

It is known that phenolic compounds such as phenol per se, resorcinol,alkyl phenols, i.e. cresols, xylenes, phloroglucinol, etc. react withaldehydes (commonly formaldehyde) or ketones to form a variety ofproducts. The nature of the resinous product depends on the choice ofthe phenolic compound and the aldehyde or ketone and on the conditionsof the reaction. Phenolic-formaldehyde resins are of two main types. Theresins resemble either the phenol alcohols or thedihydroxydiphenylalkanes in basic structure. If they are prepared with.an excess of formaldehyde and an alkaline catalyst they will resemblethe phenol alcohols and have methylol side or end groups. The molarratio of formaldehyde to phenolic compound used may vary in a ratio from1:1 to 3:1

r 1 t CH iin n=1 to 25.

Such resins are often referred to as resoles. They are capable of beingcured by the application of heat and sometimes acids, cure resultingthrough condensation of the methylol groups. By cooling the resin thereactions may be conveniently stopped, or at least effectively retarded,anywhere between the addition of the formaldehyde and the final curingprocess. To resume the reaction, the temperature is raised or an acidiccatalyst is added. Since there is no sharp break in these reactions suchresins have been termed the One-Stage resins.

The majority of the One-Stage resins employ formaldehyde as thealdehyde, although certain other aldehydes may be used. Formaldehyde ispreferred because of its high reactivity and freedom from sidereactions.

On the other hand, if the phenolic resin is prepared with an acidiccatalyst and less than a mole of formaldehyde per mole of phenoliccompound, the resin will resemble a dihydroxydiphenylmethane instructure, e.g., the chains are phenol ended. The molar ratio offormaldehyde to phenolic compound used may vary anywhere from 1:2

to 1:1, e.g.:

I- OH 1 13 CH2 HOCHF CHzOH States Patent of the Novolak resin representsone process and the addition of the curing agent represents a separateand distinct process, resins based on a Novolak resin and a curing agentare referred to as Tw0Stage resin.

Thermosetting phenolic-formaldehyde resins have certain inherentdrawbacks which prevent their full commercial use as coating materialsfor the formation of films. In other words, such resins are brittle andhave extremely poor resistance to flaking or cracking. These drawbacksare attributable to the lack of flexibility, elongation and adhesion ofthe cured film resulting from such phenolic-formaldehyde resins.Attempts to overcome these defects by incorporating any of thecommercially available plasticizers yielded no improved results. Dioctylphthalate, which is one of the most versatile plasticizers for varioustypes of resins, proved ineffective in imparting flexibility andresistance to flaking or cracking of phenolic-formaldehyde resins.

It is an object of this invention to overcome the foregoing difflcultiesand to provide a plasticized phenolicformaldehyde resin which possessesexcellent flexibility, elongation, and resistance to flaking orcracking.

Other objects and advantages will become more clearly apparent from thefollowing specification.

I have found that phenolic-formaldehyde resins of the phenol-alcoholtype are successfully plasticized by employing a mixture of 30-100 partsby weight of a condensation product of polyoxy propylene or polyoxypropylene glycol with ethylene oxide or the condensation product of thesequential addition of propylene oxide and ethylene oxides with ethylenediamine (Tetronic Polyol) and 1-15 parts of an organic titanium chelateper parts by weight, based on the non-volatile content, of aphenolic-formaldehyde resin. The latter is normally prepared in solutionform, i.e. in volatile solvents such as alcohols, ketones, etc. Filmscast from such a mixture display excellent flexibility and resistance toflaking or cracking. The polyoxypropylene glycol, thepolyoxyethylene-polyoxypropylene-polyoxyethylene glycol, or tetronicpolyol, and the organic titanium chelate is merely blended in theaforestated ratios with the phenolicformaldehyde resin and the resultingsolution employed in the preparation of coatings, films, etc., in theWell known manner.

The phenolic-formaldehyde resins employed in accordance with the presentinvention are readily available on the open market and the procedure fortheir preparation is well known to those skilled in the art. As aconsequence, references to literature or patents need not be madeherein. However, for purposes of illustration, a procedure which yieldsa phenolic-formaldehyde resin soluble in lower alcohols such asmethanol, ethanol, 11- propanol or isopropanol, or ketones, glycolethers, dioxane, and similar polar solvents is as follows:

To a S-necked resin flask, equipped with a stirrer, thermometer andreflux condenser, were added 927 parts by weight of phenol, 927 parts byweight of formaldehyde (40% aqueous solution) and 10 parts by Weight ofconcentrated ammonia. The mixture was refluxed with agitation until adrop of the reaction mixture cures into a resinous mass on a hot plateat a temperature of 200 C. in 1 /2 seconds. When this stage is reached,the resin is then dehydrated at 50 C. and 26" vacuum for a period of 3/2 hours during which the temperature is finally raised to 100 C. Theresin is then dissolved in a lower alcohol such as methanol, ethanol,isopropanol to yield a 45-70% solution, preferably a 50% solution. Inthis case, ethanol was employed as the solvent to yield a 50% solution.The resulting phenolic-formaldehyde resin in solution is of thephenol-alcohol type.

The polyoxypropylene condensation product with ethylene oxide, morespecifically called a polyoxyethylenepolyoxypropylene-polyoxyethyleneglycol which is blended with the organic titanium chelate ischaracterized by the following general formula:

wherein x represents a numeral ranging from or 1 to 40 and y representsa numeral ranging from 15 to 40. It is to be noted that when x is zerothe product is polypropylene glycol or polyoxypropylene compound. Thepolyethoxy-polypropoxy glycol is readily obtained by polymerizingpropylene oxide to a molecular weight range of 800 to 2500. Theresulting polyoxypropylene compound is water insoluble or hydrophobic.50 to 90 parts of the polyoxypropylene are then reacted with to 50 partsof ethylene oxide to yield a polyoxyethylene-polyoxypropylene-polyoxyethylene glycol having the foregoing general formulaand a molecular weight ranging from 1000 to 11,000. The condensation ofpropylene oxide to yield polyoxypropylene of molecular weights of 800 to25,00 and the further condensation thereof with ethylene oxide isaccomplished by conventional means well known to those skilled in theart. These products are commercially referred to as being prepared bythe sequential addition of propylene and ethylene oxides to propyleneglycol. They are sold under the brand name of Pluronics.

As illustrations of suchpolyoxyethylene-polyoxypropylene-polyoxyethylene glycols or Pluronics,the following were prepared by conventional means:

90 parts by weight of polyoxypropylene compound having a molecularweight of 800-1000 were treated with 10 parts of ethylene oxide to yielda compound having the following structure in which the mole ratios areaverage:

HO z t 1 (CBHGO) 2 4 1 60 parts of polyoxypropylene compound of amolecular weight of 1000 to 1200 were condensed with 40 parts ofethylene oxide to yield a compound having the following structure inwhich the mole ratios are average:

80 parts of polyoxpropylene compound having a molecular weight of1500-1800 were condensed with parts of ethylene oxide to yield acompound having the following structure in which the mole ratios areaverage:

50 parts of polyoxypropylene compound having a molecular weight of1800-2100 were condensed with 50 parts of ethylene oxide to yield acompound having the following structure in which the mole ratios areaverage:

70 parts of polyoxypropylene compound having a molecular weight of2100-2500 were condensed With 30 parts of ethylene oxide to yield acompound having the following structure in which the mole ratios areaverage:

Polypropylene glycol having an average molecular weight of approximately800.

Polypropylene glycol having an average molecular weight of approximately1025.

Polypropylene glycol having an average molecular weight of approximately2025.

In lieu of the foregoing polyoxyethylenepolyoxypropylene-polyoxyethylene glycols, and polyoxypropylene glycols,compounds characterized by the following general formula may be used incombination with the organic titanium chelate in the aforementionedproportions:

wherein n=a numeral ranging from 4 to 20 and m=a numeral ranging from 1to 30. These compounds are prepared by the sequential addition ofpropylene and ethylene oxides to ethylene diamine in accordance withconventional procedure which is well known to those skilled in the art.Briefly, they are prepared by reacting propylene oxide with 1 mole ofethylene diamine to give a base material having a molecular weight rangeof 292 to 4500. From 20-90 parts of the resulting base material are thenreacted in the conventional way with 10-80 parts of ethylene oxide. Theyare all commercially available under the brand name of Tetronic Polyolshaving approximate molecular weights of 1700 to 12,000.

As specific illustrations of such Tetronic Polyols, the following wereprepared and utilized in accordance with the present invention:

Base Ethylene Material Oxide Molecular Parts Parts Weight:

1 Average molecular weight.

The organic titanium chelates that I employ are readily obtained in theusual manner by reacting 1 mole of a titanium ortho ester with 2, 2.2, 3or 4 moles of either octylene glycol (2-ethylhexanediol-1,3)triethanolamine, triethanolamine-N-salts of fatty acids such as butyric,caproic, caprylic, capric, undecylic, myristic, palrnitic, oleic,linoleic, stearic or any of the fatty acids whether saturated orunsaturated so long as they contain from 4 to 18 carbon atoms.

The titanium ortho esters utilized in the preparation of thecorresponding chelates are characterized by the following generalformula:

Ti(OR) wherein R represents an alkyl group of one of the 3 to 18 carbonatoms, e.g. propyl, butyl, hexyl, octyl, nonyl, decyl, dodecyl, cetyl,octadecyl, etc. As illustrations of such titanium ortho esters, I havefound the following to be especially adaptable for the preparation ofthe corresponding chelates:

Tetraisopropyl titanate Tetra n-butyl titanate Tetra n-amyl titanateTetrahexyl titanate Tetra-Z-ethylhexyl titanate T etraheptyl titanateTetraoctyl titanate Tetranonyl titanate Tetradecyl titanateTetrahendecyl titanate Tetradodecyl titanate T etracetyl titanateTetrastearyl titanate "The organic titanium chelates (all of which arecommercially available under various brand or trade names) are, aspointed out above, readily obtained by reacting in the conventionalmanner 2, 2.2, 3 or 4 moles of the chelating compound such as octyleneglycol, triethanolamine, a fatty acid salt of triethanolamine or a fattyacidof 3 to 18 carbon atoms with 1 mole of any one of the above titaniumortho esters. The triethanolamine titanate N-salts of fatty acids arereadily obtained by reacting 2 moles of triethanolamine with 1 mole ofthe titanium ester of l or 2 moles of a fatty acid. All of the chelatesutilized in accordance with the present invention are characterized bythe following general formula:

O-Y:OH nlo-i ij o R1 -Y OH wherein R represents either hydrogen or analkyl radical from 3 to 18 carbon atoms and Y represents the chelatingradical which is linked to two or more electron donating atoms such asoxygen or hydrogen and characterized by octylene glycol, triethanolamineor a fatty acid. Such titanium chelates can also be prepared by reactingglycols of 4 to 8 carbon atoms or amino alcohols such as triethanolaminein ratios of 2, 2.2, 3 or 4 moles per mole of titanium ortho-ester. Thetitanium chelates based on amino alcohols can be further reacted withpartial or complete neutralization with fatty acids of 3 to 18 carbonatoms.

As examples of titanium chelates that may be used in conjunction withany one of the foregoingpolyoxyethylene-polyoxypropylene-polyoxyethylene glycols, the

following are illustrative:

6 Example I A film of the resin solution prepared as above described wascast on a 20 gauge automotive steel panel while employing a gauge with a5 mil clearance. After /2 hour of air drying, the film was baked for aperiod of /2 hour at a temperature of 175 C. The cured film had athickness of approximately 1 mil. The film was then evaluated forflexibility while employing a General Electric impactflexibility testerand was found to give an impact elongation of 1%. This low figure isclearly indicative of a very brittle, poorly plasticized film.

The foregoing flexibility tester is commercially available on the openmarket and entails a solid metal cylinder which is dropped through aguide trap from a slide of approximately 4 feet. The impactor strikesthe reverse side of the coated test panel which is supported by a rubberpad so that the circular imprint of the impactor is barely definable inthe panel metal. Each end of the impactor is studded with a group ofprotruding spherical knobs arranged in a circle. After impact, the filmis distended according to the curvature of the spherical surface forminga knob. The percentage elongation of the film is a function solely ofthe geometry of the knob itself, and is not dependent upon the rate ofdraw, thickness of the metal panel or other dimensions. This apparatuswas chosen because it is ideal for testing resin films for theirflexibility, either air dried or baked on a metal panel.

prepared above, were added 25 parts of a polyoxypropylene compound ofillustration A. A film was cast on a Molar Proportions Organic TitaniumChelate i Ohelating Compound Ti Acid Employed as Solution 1. Octyleneglycol titanate (OGT-21) 2 moles Octylene glycol (2- 1 in butanol.

ethyl-hexanediol-L3). 2. Octylcne glycol titanate (OGT2.?1) 2.2 molesoctylene glycol (2- 1 38% in butanol.

ethyl-hexanediol lfil. 3. Octylene glycol titauate (OGT31) 3 molesOctylene glycol (2- l 40% in butanol.

ethy1-hexanediol-L3). 4. Octylene glycol titanate (OGT-41) 4 molesOctylene glycol (2- 1 Do.

ethyl-hexanediol-L3). 5. Tricthanolamine titanatc (TAT-21) 2 molesTriethanolamine l 59% in lsopropanol. 6. Triet)hanolaminetitanate-N-oleate (TAT-O- d 1 l Do.

211 7. Tricthanolamine titanate-N-oleate (TAT-O- 1 2 Do 21 8.'lriethanolamine titanate-N-stearate (TAT-S- do l 1 stearic Do.

211). 9. Triethannlamine titauatc-N-linseed acids salt 1 1 linseed fattyDo.

(TAT-L-Qll). acids.

1 Trade name.

It is to be'noted at the outset that the use of anyone of thepolyoxyethylene-polyoxypropylene-polyoxyethylene glycols, andpolyoxypropylene glycols per se, including mixtures thereof, does notyield a plasticized phenolicformaldehyde resin having resistance toflaking or cracking. Similarly, the use of the Tetronic Polyol per se,as well as the use of the organic titanium'chelate alone does not yielda plasticized film which will exhibit resistance to flaking or cracking.It is only the combination of the organic titanium chelate either withthe Tetronic Polyol or with thepolyoxyethylene-polyoxypropylene-polyoxyethylene glycol orpolyoxypropylene glycol in the aforementioned proportions which yields acompletely plasticized film having unusual resistance to flaking orcracking as will be shown hereinafter.

The following examples will illustrate the various ways in which thephenolic-formaldehyde resin of the phenolalcohol type may be plasticizedto yield a composition which in film form possesses excellentflexibility and resistance to flaking or cracking. All parts given areby weight. 7

20 gauge automotive steel panel while using a gauge with a5 milclearance. The coated film was air dried for /2 hour followed by bakingat 175 C. for /2 hour period.

The cured film had a thickness of approximately 1 mil and when evaluatedwith the General Electric impact .elongation tester gave an impactelongation of approximately.5%. This figure indicates a poorlyplasticized film which is unsuitable wherein resistance to flaking orcracking is a prerequisite.

Example 111 Example IV To parts of the phenolic-formaldehyde resinprepared as above, were added 25 parts of polypropylene glycol having anaverage molecular weight of 1500 '7 (illustration B). The mixture wasstirred and a film cast in the same manner as in Example I. The driedand cured film gave an impact elongation of 1%, thus indicating a poorlyplasticized and very brittle film.

8 Example VI A large quantity of phenolic-formaldehyde resin wasprepared in'accordance with the foregoing procedure. In

E l V addition, a sufficient quantity of a commercially availxamp e ablephenol-formaldehyde resin in alcohol, sold under the To 100 parts of thephenolic-formaldehyde resin prebrand name of Resinox P-97 (50% of resinin alcohol) pared as above, were added 15 parts of octylene glycol wasobtained on the open market and utilized for test titanate (commerciallyavailable under the brand name purposes. Both of the resin solutionswere allocated into OGT-2.21). The mixture was stirred and a film castin separate portions each containing 100 parts by weight the same manneras in Example I. The dried and cured of the resin based on thenon-volatile basis to which film gave an impact elongation of /z% thusindicating was added (1) a mixture consisting of polyoxyethylenea poorlyplasticized and very brittle film. polyoxypropylene-polyoxyethyleneglycol and organic From the foregoing example, it is clearly evidentthat titanium chelate, (2) a mixture consisting of a Tetronic the use ofeither a polyoxypropylene glycol, polyoxy- Polyol and organic titaniumchelate, and (3) a mixture ethylene-polyoxyp-ropylene-polyoxyethyleneglycol, Teof polypropylene glycol and organic titanium chelate in tronicPolyol or an organic titanium chelate by itself as various proportions.The resulting solutions were cast as a plasticizer inphenolic-formaldehyde resins of the in Example I and then evaluated inthe General Electric phenol-alcohol type yield a very poorly plasticizedfilm impact elongation tester. The results obtained are tabuhaving noresistance to flaking or cracking. The new lated in the followingtables:

TABLE 1 Parts of Pheno1-Form Parts of aldehyde Resinox P-97 PercentOrganic Titanium Ohelate Parts Pluronie" Parts Resin Solution SolutionG.E. Im-

of illustration based on pact Elon- Based on non-volatile gationNon-volatile Content Content 5 60 Do 10 .60 3 40% in butanoL 5 60 1General formula: HOCH z)n(|J -0 H3 CH3 TABLE 2 Parts of Phenol- Parts ofPercent Organic Formaldehyde Resinox P-97 G. E. Titanium Parts TetronieParts Resin Solution Solution based Impact Ghelate Polyol ofIllustration on non-vola- Elongation Based on Nontile Content 1 F 20 2.5G 40 5 H 60 10 I 60 15 J 60 5 K 60 it a 60 .5 N 23 and unexpectedfeature in accordance with the present invention is that when either theaforementioned glycol or the aforementioned Tetronic Polyol is employedtogether with the organic titanium chelate in the aforementionedproportions, at new effect is obtained yielding complete plasticizationand as a consequence a film which is highly resistant to flaking orcracking. The use of organic tin or zirconium chelates by themselvesproduces no beneficiai effect whatsoever When employed alone as aplasticizer or together or in conjunction with the aforementioned glycolor Tetronic Polyol in the aforementioned concentrations.

From the foregoing tables it becomes clearly manifest that a mixture ofat least 30 parts by Weight of either the aforementioned glycols orTetronic Polyols and 1-15 parts by Weight of the organic titaniumchelate per parts of the phenolic-formaldehyde resin containing 100%solids, yields exceptionally good plasticized films possessingresistance to cracking or flaking. The high percent of impact elongationis always indicative of a very well plasticized film.

In order to determine What effect varying amounts of the organictitanium chelate would have on a finished film, separate solutions inethanol were prepared in accordance with the foregoing procedure and thefollowing results obtained:

10 4. A heat curable coating composition according to claim 3 whereinthe fatty acid is oleic acid.

All parts by weight based on non-volatile basis Components SolutionResinox P-97 67 67 67 67 67 67 67 67 67 Pluronic" A 33 33 33 33 33 33 4843 40 Octylene glycol titanate (O (EFT-2.21) 1 2. 5 10 0 6 0 (3.13.Impact, Elongation, perover over over over cent 5 2O 40 60 60 60 10 10When Pluronic A was replaced by an equivalent amount of Tetronic PolyolsR, S and T, identical results were obtained as follows:

5. A heat curable coating composition according to claim 3 wherein thefatty acid is stearic acid.

6. A process of obtaining a heat cured film having G.E. Impact,Elongation: over over over R percent 40 60 60 60 over 60 Instead ofemploying straight alcohol solutions of the phenolic-formaldehyderesins, it is possible to incorporate various fillers and pigmentstogether with other organic solvents compatible with alcohol to yieldvarnishes and lacquers which upon baking will yield coatings havingextreme flexibility and resistance to cracking or flaking.

I claim:

1. A heat curable coating composition comprising 100 parts by weight ofa phenol-formaldehyde resin, 100 parts by weight of a compoundcharacterized by a formula selected from the class consisting of thefollowing formulae:

2 4 )X( 3 6 z 4 )xand H(C2H4 )m(Cs eO)n NCH2CH2N H(C2H40) (CaH50) ?CaHO) (C5H40) H wherein m represents a numeral ranging from 1 to 30, nrepresents a numeral ranging from 4 to 20, x represents a numeralranging from 0 to 40, represents a numeral ranging from 15 to 20, and 1to 15 parts by weight of an organic titanium chelate having thefollowing general formula (|)Y:OH R10'ri::o R1

r on wherein R represents a member selected from the class consisting ofhydrogen and an alkyl group of from 3 to 18 carbon atoms, and Yrepresents a chelating radical selected from the class consisting of-cH,-OH- H- and G NE:-

2. A heat curable coating composition according to claim 1 wherein thechelating radical is 3. A heat curable coating composition according toclaim 2 wherein the triethanolamine chelate radical is neutralized witha fatty acid of from 3 to 18 carbon atoms.

flexibility and resistance to flaking and cracking comprising coating asurface with a composition comprising parts by weight of aphenol-formaldehyde resin, 30-100 parts by weight of a compoundcharacterized by a formula selected from the class consisting of thefollowing formulae:

wherein m represents a numeral ranging from 1 to 20, n represents anumeral ranging from 4 to 20, 2: represents a numeral ranging 0 to 40,and y represents a numeral ranging from 15 to 40 and 1 to 15 parts byweight of an organic titanium chelate having the following generalformula:

0-YOH nlo-if o R1 wherein R represents a member selected from the classsisting of hydrogen and an alkyl group of from 3 to 18 carbon atoms, andY represents a chelating radical selected from the class consisting ofNo references cited.

, UNITED STATES PATENT OFFICE QERTIFTCATE OF CUERECTTGN Patent No 2 956966 October 18 1960 Robert Steckler It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 3 line 2O for 25,00 read 25 OOO column 9 line 4L8 for "20" read4O Signed and sealed this 14th day of November 1961;

(SEA L) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Gommissioner of PatentsUSCOMM-DC i

1. A HEAT CURABLE COATING COMPOSITION COMPRISING 100 PARTS BY WEIGHT OFA PHENOL-FORMALDEHYDE RESIN, 30-100 PARTS BY WEIGHT OF A COMPOUNDCHARACTERIZED BY A FORMULA SELECTED FROM THE CLASS CONSISTING OF THEFOLLOWING FORMULAE: